Never mind! Celebrities who unretired

Athletes, and boxers, in particular, are notorious for being unable to stay retired. "The Greatest" was no different. While still holding the heavyweight belt in 1979, Ali retired at age 37. He came back the following year to fight, and lose badly to, Larry Holmes. Despite calls for him to retire for good, Ali, seen here in 1983 with President Ronald Reagan, fought one last time on Dec. 21, 1981, losing a 10-round decision to Trevor Berbick.

Whatever their reasons, more than a few stars have decided to walk away from their chosen fields only to get the itch and return -- some more than once. Take a look at some celebrities who have "unretired."

Hillary Clinton's office said "nothing nefarious was at play" when the former secretary of state used her personal email address, rather than one provided by the State Department, during her four years as America's top diplomat.